Network to Serial » VScom Serial Device Servers

ID #1111

Your NetCom Plus sends the wrong Hardware Address in DHCP Requests

This is not an error in the NetCom Plus, instead a wrong behaviour of the DHCP server software.

First the quick and proven workaround:

  1. Configure the Hardware Address and the intended IP Address in the DHCP Server
  2. Configure the NetCom Plus for static IP Address instead DHCP, and use the reserved IP Address.

This way the DHCP server will never offer the IP Address to any device, effectively reserving it. And the NetCom Plus uses the intended IP configuration.

The problem in the DHCP Server:

The NetCom Plus use the standard DHCP-Client dhcpcd. At first the Hardware Address of the NetCom Plus is in the defined header field. Also there is the option of Client Identifier, this content is just the MAC Address in binary format. So Option 61 in the DHCP Request is filled with 6 bytes.
According to RFC 2132 (read here) the only criterion for this is uniqueness of the ID and this is fulfilled by NetCom Plus. The Client identifier is defined as opaque, thus no evaluation is mandatory.

The problem with the DHCP server is an intended evaluation which in your case fails. The software attempts to interprete the data and fails on this. Either you can configure the DHCP server to handle this different or you may use the above workaround.

This problem is very rare. Therefore we can not change the format of the Client Identifier without interrupting operation with most customers.



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Last update: 2018-07-24 15:54
Author: Support
Revision: 1.1

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